photobombing 

Intentionally posing in other people's photos, for a later surprise.
Usually people making funny faces in the background, without the knowledge of the main subjects of the photo.

Jim is always photobombing, he messed ups some of the best photos from the wedding.

photobombing by U8IK May 6, 2008

photobomb 

(verb)- to drop in a photo unexpectedly...to hop in a picture right before it is taken.

sarah: hey why is jimmy in the background of our prom picture?
ryan: idk, he must have photobombed it at the last second.

photobomb by jervis_star1 June 27, 2008

Photobomb 

An otherwise normal photo that has been ruined or spoiled by someone who was not supposed to be in the photograph.

The most common photobomb is someone in the background making a face.

Photobomb by Teresa from OK November 16, 2009

Reverse Photobomb 

(verb)- a photo taken without the knowledge and awareness of the person in the foreground, but known and planned by the person in the background and the photo taker. Basically the reverse of a traditional photobomb, where someone unsuspectingly jumps into the background of a people-posed photo.

Lark: Hey Jan, let's reverse photobomb Craig!
Jan: I'll run up behind Craig and pose. If he see's me, he'll have no idea what I'm doing.
Lark: This is going to be a great RPB pic! Let's RPB Gike Mallego next!

Reverse Photobomb by Captain Incredible x Infinity June 2, 2015

photobombed 

When people hilariously ruin your nice little picture by jumping in.

NO WAY!! We got photobombed in every single one of our prom photos!

photobombed by Luxferre May 15, 2008

photobomb 

Any time the background of a picture hijacks the original focus.

Uncle Bob's hairy ass totally photobombed that picture.

photobomb by photobomber May 9, 2009

photobomber 

Often intoxicated dude that works his way stealthily into your photographs, completely ruining another potentially awesome picture pf girls making out

"damn that photobomber for messin my pic!"

photobomber by mike deguzi June 19, 2008